WINGED PETIOLE.

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render aquatic plants susceptible of vegetation on the mountains, she bestows aqueducts on their leaves; but when, on the contrary, she means to place mountain plants by the water's side, she withdraws it." * He advances much more to the same purpose, and indeed the theory is pretty; but it is at the same time, as Gerard would say, "all and every part of it false and most untrue."

4. PETIOLUS alatus, a winged petiole; when, as in the winged stem, its sides are expanded into a leafy border, as in the leaves of the Orange-tree; Fig. 21. (d)

There may occur a chance of error here, of which I must warn you. There are certain appendages of plants named stipules, which will be described farther on. Now, sometimes these stipules ad here laterally to the petiole, and give it somewhat of a winged appearance, which might lead you into the error of supposing that such a petiole should be called a petiolus subalatus, that is, a partially winged foot-stalk. Pull the leaf of a rosebush, and you will perceive this, as at Fig. 21. (a) is the petiole, and (bb) the stipules adhering to it. Fig. 21.

You will remark also, that from the principal leaf-stalk in the rose, there spring out secondary ones. The rose-leaf is compound, that is, not consisting of a single leaf, as in the aspen, but of more than one. But generally when the leaf is compound, the leaf-stalk, as in this instance, is compound also; and hence,

5. PETIOLUS simplex, a simple leaf-stalk, as in the poplar, and all plants which have simple leaves; and,

6. PETIOLUS compositus, a compound leaf-stalk, as in the rose, &c. and the secondary or partial petioles, arising from the principal, are named petioluli; therefore,

7. PETIOLULUS, a partial leaf-stalk, as at (c).

8. PETIOLUS cirriferus, a tendrilled leaf-stalk. When the petiole terminates in, or protrudes a tendril, from any part of its surface.

9. PETIOLUS vaginans, when it invests the stem like a sheath, as in grasses.

We shall now attend to the leaves themselves; and, in the first place, it is very obvious, that they are not limited to any one part of the plant. They spring in some from the root, in others from the stem, in some from the branches, and in many from all these parts.

FOLIUM, means a leaf; FOLIA, leaves.

1. FOLIUM radicale, a radical, or root-leaf, means, of course, a leaf springing out from the root,

examples of which are very frequent; familiar ones occur in the primrose, cowslip, and violet.

2. FOLIUM caulinum, a stem-leaf, equally common. 3. FOLIUM rameum, a branch-leaf (ramus, a branch). This sometimes differs from the leaves on the stem.

4. FOLIUM axillare, an axillary leaf. When a branch leaves a stem, the angle between the two is named an axilla; and hence a leaf, peduncle, &c. rising from such angle, is called axillary.

5. FOLIUM florale, a floral leaf, placed close to the flower, as in Orchis, in which there is a leaf at the base of each flower-stalk. There is a leafy appendage found in some plants which has the name of bractea or bracte. This is often translated "floral leaf," but improperly, for as is observed by Martyn, "it seems better to preserve the term Bractea, or Bracte, than to translate it: for Linnæus frequently calls leaves which are near the flower, Floral leaves, when they differ from the other leaves, though they are not properly bractes." 6. FOLIUM seminale, a seminal or seed-leaf (semen, a seed, Lat.).

If you plant the seed of a lupin, you will find that after some days it will protrude above the earth, in form of two thick, orbicular, fleshy leaves. These, before the seed germinated, composed its two sides, halves, or cotyledons, as they are called. The juices they contain in this leaflike state go to the nourishment of the plant, and

by the time that they are exhausted and dead, the root is strong enough to depend on its own exertions for support. These temporary but very important leaves are often attacked by insects, and destroyed before the root has acquired strength to perform its office, and in consequence, the whole plant perishes. In this way turnip crops are blighted by the fly.

As leaves are extremely various in shape, and as they very often resemble in outline, some familiar or well-known object, nothing can be more natural than to name them after such objects. If a leaf resemble a lyre, what term can be used for it more apposite than lyrate? or if a sword, than ensiform; or a lance, than lanceolate? By arranging leaves, whose appellations are thus taken from certain classes of bodies, together, I think the memory will be assisted, and I shall, so far as the subject will admit, adopt that plan. We shall first attend to

SUCH LEAVES AS ARE NAMED FROM PARTS OF

THE ANIMAL BODY.

7. FOLIUM cordatum, a cordate, or heartshaped leaf (cor, the heart, Lat.). This leaf bears a nearer resemblance to the heart on playing cards, than to a real heart. See Fig. 22. (a) It is common, and in many plants very beautiful, as in the broad-leaved and other species of birthwort, black bryony, &c.

8. FOLIUM reniforme, reniform, or kidney-shaped

(ren, a kidney, Lat.), as in ground-ivy, white saxifrage, the Anemone palmata, &c. Fig. 22. (b) and Fig. 29.

9. FOLIUM linguiforme, or lingulatum; a linguiform, or tongue-shaped leaf (lingua, a tongue, Lat.); "linear and fleshy, blunt at the end, convex underneath, and having usually a cartilaginous border, as in Mesembryanthemum, Aloe, Hoemanthus coccineus." Martyn's Language of Botany.-"Of a thick, oblong, blunt figure, generally cartilaginous at the edges, as Mesembryanthemum linguiforme, Dendrobium linguiforme, and several species of Saxifrage." Smith's Introduction.

10. FOLIUM auriculatum, auriculate, or earshaped; auritum also is used (auris, an ear, Lat.), having two lobes, or two leaflets at its base. Fig. 23. (a) and (b).

11. FOLIUM capillare, or capillaceum; long and hair-like (capillus, a hair, Lat.).

12. FOLIUM ciliatum, ciliated (cilium, an eye-lash, Lat.). This term applies to the margin of the leaf, and means that it is set with hairs, placed at some distance from each other, of equal length, parallel, and bearing a resemblance to the eye-lashes. Fig. 23. (c)